• Aucun résultat trouvé

Neoproterozoic to Lower Paleozoic Sequences of the Congo Shield: Comparisons Between the Congo and Its Peripheral Basins


Academic year: 2021

Partager "Neoproterozoic to Lower Paleozoic Sequences of the Congo Shield: Comparisons Between the Congo and Its Peripheral Basins"

En savoir plus ( Page)

Texte intégral


Neoproterozoic to Lower Paleozoic Sequences of the Congo Shield: Comparisons Between the Congo and Its Peripheral Basins


E´tienne Kadima Kabongo, Damien Delvaux, Michel Everaerts, Mwene Ntabwoba Stanislas Sebagenzi, and Francis Lucazeau

6.1 Introduction

The Congo Basin (CB) is the largest and the least explored African continental sedimentary basin. Outcrop scarcity, intense weathering and dense forest constitute obstacles to undertake direct geologically-based exploration programmes, highlighting the importance of airborne and ground-based geophysics. In the 1950s, the ‘ Syndicat pour l’e´tude ge´ologique et minie`re de la Cuvette congolaise ’ conducted refraction and reflection seismic, gravimetric and magnetic field surveys across the central parts of the CB (Evrard 1957). During the seismic surveys, 117 refrac- tion stations were employed in the basin interior, and 7 reflection lines were recorded along rivers (Evrard 1960).

In addition, about 6,000 gravity and magnetic measurements were made with an average station spacing of 5 km along rivers and dirt roads (Jones et al. 1960). Moreover, two fully- cored stratigraphic wells down to ca. 2,000 m had been drilled in the 1950s, reaching red sandstones at the bottom, that were interpreted as pre-Carboniferous (Cahen et al. 1959, 1960).

Using these geophysical and well data, Evrard (1957, 1960) and Jones et al. (1960) first imaged the structure and extent of the CB and its subsurface geometry. The major refractors mapped provided the first regional overview of the

basin subsurface structure. The CB appeared deeper than previously thought, with the possible existence of several thousand meters of sedimentary rocks beneath its upper Paleozoic–Mesozoic sedimentary sequences.

Additional geophysical surveys were subsequently conducted by various petroleum companies. Exxon-Texaco shot 2,900 km of seismic reflection profiles in 1974–1976, and Japan Oil National Corporation (JNOC) performed an aeromagnetic survey and gravity measurements around Kisangani in 1984; and two additional wells, more than 4,000 m deep, were drilled (Esso Zaire 1981a, b). The interpretation of this data was first presented in an ECL (1988) report by Petrozaı¨re, of which a short summary was published by Lawrence and Makazu (1988). More detailed interpretations of the seismic reflection profiles and wells were presented as synthetic stratigraphic columns and a tectonic model by Daly et al. (1992), in which early subsi- dence of the basin was interpreted to reflect Neoproterozoic processes of rifting and thermal relaxation, followed by two regional contractional deformation phases that inverted the subsiding basin during the early Paleozoic and the late Paleozoic. The first inversion was attributed to late stages of the Pan-African orogeny in Central Africa, and the second inversion phase to far field intraplate stresses generated at the southern margin of Gondwana during the formation of the Cape Fold Belt. Daly et al. (1992) also speculated on the possible role of evaporites in enhancing deformation process at the deepest levels of the basin. Subsequently, Kadima et al. (2011a) further constrained the interpretation of some of the seismic profiles using 2D gravity and magnetic models, and delineated heterogeneous crust beneath the sedimentary sequences of the basin consistent with the inter- pretation that the central part of the basin is an intracratonic rift inverted during compressional tectonics facilitated by the presence of evaporites and salt tectonics.

Despite a renewed interest over the last decade, there are still many unanswered questions regarding the nature of the crystalline basement, the Neoproterozoic and Phanerozoic stratigraphy, as well as the structure of the CB. The E ´ .K. Kabongo ( * ) M.N.S. Sebagenzi

Laboratoire de Ge´ophysique et Ge´odynamique, De´partement de Ge´ologie, Universite´ de Lubumbashi, Lubumbashi, DR Congo e-mail: ekadimak@gmail.com; ssebagenzi@yahoo.fr D. Delvaux M. Everaerts

Geodynamics and Mineral Resources, Royal Museum for Central Africa, 3080 Tervuren, Belgium

e-mail: damien.delvaux@africamuseum.be;

michel.everaerts@africamuseum.be F. Lucazeau

Dynamique des Fluides Ge´ologiques, Institut de Physique du Globe de Paris/Sorbonne, Paris Cite´, UMR CNRS 7154, 1 rue Jussieu, 75005 Paris, France

e-mail: lucazeau@ipgp.fr

M.J. de Wit et al. (eds.), Geology and Resource Potential of the Congo Basin, Regional Geology Reviews, DOI 10.1007/978-3-642-29482-2_6, # Springer-Verlag Berlin Heidelberg 2015



crystalline basement comprises Archean to Mesoproterozoic igneous and metamorphic rocks of the Congo Shield (see de Wit and Linol, Chap. 2, this Book). Scarce outcrops, limited geological data and stratigraphic age constraints still prevent a detailed reconstruction of the Neoproterozoic history of the CB. Nevertheless, many authors have attempted to decipher the Neoproterozoic geological evolution of Central Africa and the CB in particular (Cahen 1954; Evrard 1960;

Lawrence and Makazu 1988; Daly et al 1991, 1992; Kadima 2011; Kadima et al. 2011a, b; Linol 2013; see also Chaps.

2 to 5, this Book).

Here, we re-examine the largely hidden Neoproterozoic to lower Paleozoic sequences of the CB near the centre of the Congo Shield and compare its evolution with the surrounding and partially exposed marginal sedimentary basins.

6.2 Neoproterozoic to Lower Paleozoic Sequences of the Congo Shield Flanking the CB

In Central Africa, the Neoproterozoic geological evolution is marked by a succession of major events initiated by the break-up of the Rodinia supercontinent and opening of rift- basins (e.g. West Congolian, Sembe´-Ouesso, Mbuji-Mayi, Katanga, Zambian basins), and terminating by the amalgam- ation of Gondwana and the filling of associated foreland basins (e.g. de Waele et al. 2008). Traces of these events can be observed within the Congo Shield (sensu Stankiewicz and de Witt 2013) and particularly in marginal sedimentary basins surrounding the CB (Fig. 6.1a), such as the West Congo, Sembe´-Ouesso, Bangui and Liki-Bembian basins to the West and Northwest; the Fouroumbala-Bakouma and Lindian basins to the North and Northeast; the Itombwe and Malagarazi-Bukoban basins to the East; the Katanga, Zambian and Mbuji-Mayi basins to the Southeast (Fig. 6.1b).

Studies based on shear-wave tomography (Crosby et al.

2010; Priestley et al. 2008; Ritsema and van Heijst 2000), admittance models (Downey and Gurnis 2009; Hartley and Allen 1994; Hartley et al. 1996; Pe´rez-Gussinye´ et al. 2009), kimberlite data (Crosby et al. 2010; Batumike et al. 2009), subsidence modelling (Kadima et al. 2011b; Kadima 2011) and heat flow estimations (Kadima et al. 2011b; see also Lucazeau et al., Chap. 12, this Book) suggest that the CB and surrounding Lindian and Mbuji-Mayi basins are underlain by a thick mantle lithosphere (200 km or more), with an equivalent elastic thickness of ca. 100 km (for further details see Raveloson et al., Chap. 1, this Book).

Evidence of Rodinia break-up as main mechanism of formation for some of the sedimentary basins surrounding the CB is supported by the age of magmatic intrusions

observed into these basins (Vicat and Vellutini 1987; Vicat et al. 1989; Key et al. 2001; Tack et al. 2001; Johnson et al.

2007; de Waele et al. 2008). A brief summary of the strati- graphy of these marginal basins is given below, in clockwise order as depicted in Fig. 6.1:

1. The West Congo basin contains rhyolites and felsic volcanoclastics dated at 950 Ma (Tack et al. 2001) and intruded by granitoids (e.g. in the West Congo Super- group and the Sangha-Comba Aulacogen). These volcano-magmatic series have been considered to repre- sent a continental rift sequence related to the break-up of Rodinia and the opening of the Adamastor Ocean with the deposition of passive margin sediments (Alvarez 1995a, b; Tack et al. 2001). These sequences are overlain by the Ediacaran-Cryogenian West Congo Group comprising a succession of siliciclastics interbedded with diamictites and carbonates (Frimmel et al. 2006; see also Delpomdor et al., Chap. 3, this Book).

2. The Sembe´-Ouesso basin exposed in the Republic of the Congo (Congo-Brazzaville) contains sequence of schist and quartzite, overlain by a pelitic and sandstone sequence, and in turn by the Dja tillite, estimated at ca.

950 Ma (Vicat and Vellutini 1987). Dolerites intrude all these sequences; and their emplacement is interpreted to be related to crustal extension leading to basin subsidence in a failed rift (Vicat and Vellutini 1987; Vicat et al. 1989;

Vicat and Pouclet 1995).

3. The Fouroumbala-Bakouma and Bangui basins in the Central African Republic (CAR), the Liki-Bembian, Lindian, Itombwe syncline in the Democratic Republic of Congo (DRC), as well as the Malagarazi-Bukoban basin in Burundi and Tanzania all have been recognized to be Neoproterozoic in age, based on limited radiometric dating and lithostratigraphic correlations (Alvarez 1995a, b, 1999; Poidevin et al. 1980/1981; Poidevin 1985, 2007;

Deblond et al. 2001). The age of the Bakouma Formation was first estimated at ca. 840 50 Ma (Poidevin 1996), although Alvarez (1999) obtained a whole rock Rb-Sr date for these rocks of ca. 683 11 Ma. Magmatic intrusions have been documented, in particular in the Fouroumbala-Bakouma, Bangui, Itombwe and Malagarazi-Bukoban basins (Waleffe 1988; Poidevin 1976, 1979; De Paepe et al. 1991; Tack 1995; Deblond et al. 2001). Amygdaloid lava belonging to the Malagarazi Supergroup has been dated at 795 7 Ma (Deblond et al. 2001). Syenite, dated at 700 50 Ma, intrude sediments filling the Itombwe basin (Villeneuve 1983).

4. The Katangan and Zambian basins, now part of the Lufilian (Arc) fold-and-thrust belt, developed during two magmatic events between 880 Ma and 750 Ma (Porada 1989; Armstrong et al. 2005; Johnson et al.

2005), and were subsequently deformed during the Pan-


African orogen, between ca. 700 Ma and ca. 530 Ma (Cailteux 1994; Hanson et al. 1994; Porada and Berhorst 2000; Key et al. 2001; De Waele et al. 2008). These basins comprise the Roan, Mwashya, Nguba and Kundelungu Groups. The Roan Group overlies the 877 11 Ma Nchanga granite (Armstrong et al. 2005), and the Mwashya Group contains 765 5 Ma intrusions (Key et al. 2001).

5. The Mbuji-Mayi basin is a SE–NW trending intracratonic failed-rift basin. It contains a lower clastic sequence BI and an upper carbonate sequence BII (Raucq 1957, 1970;

Cahen et al. 1984; Delpomdor, et al. 2013a). The pres- ence of dolerite intrusions and pillow lavas were taken as evidence of extensional magmatism during the deposition of the Mbuji-Mayi sediments (Raucq 1957, 1970; Cahen et al. 1984). Isotopic data from the Mbuji-Mayi carbo- nates and the presence of pseudomorphs of anhydrite and gypsum filling veins and fractures reflect deposition and early diagenesis in marine and evaporitic conditions (Delpomdor, et al. 2013b; see also Delpomdor et al., Chap. 4, this Book). The minimum age of sedimentation for the Mbuji-Mayi Supergroup was first estimated by amygdaloid basalts interpreted as capping the entire sequence and dated at ca. 940 Ma (Cahen et al. 1984).

Delpomdor et al. (2013a) further constrained the deposi- tion of this Group between 1174 22 Ma and ca.

800 Ma; and the carbonate BII Group is now dated at 760–820 Ma by Carbon and Strontium chemical stratig- raphy (Delpomdor et al., Chap. 4, this Book) and the sliciclastic BI Group is either older than 880 Ma or aged between 880 Ma and 850 Ma. Following this second hypothesis, the Mbuji-Mayi Supergroup would be coeval with the Roan Group in the Katanga and Zambian basins, reflecting a similar early Neoproterozoic exten- sion event.

6.2.1 Neoproterozoic Siliciclastic and Carbonate Sequences

The Neoproterozoic basins surrounding the CB have consis- tent (similar) stratigraphic successions. In most of them, a carbonate unit, of variable thickness, overlies a basal silici- clastic sequence comprising silts, sandstones and conglo- merates. The Neoproterozoic carbonates are in turn overlain by relatively thick and persistent siliciclastic sequences.

For example, in the West-Congo basin, the Schisto- Calcaire Subgroup overlies the Haut Shiloango Subgroup and is overlain by the Mpioka Subgroup. The Haut Shiloango Subgroup comprises predominantly carbonates, with increasing siliciclastics upwards (Delpomdor et al.

2014; and Chap. 4, this Book). The Mpioka Subgroup consists of up to 1,000 m of molasse-like sequences com- prising conglomerates, sandstones and argillites (Alvarez 1995a, b; Tack et al. 2001; Frimmel et al. 2006). Similarly, in the Bangui basin, the basal Kembe sequence of conglomerates is overlain by the Bimbo sandstones and the Bangui carbonates. Here, no clastic sequence is observed above this carbonate sequence (Poidevin 1976).

A similar succession is observed in the Fouroumbala- Bakouma basin (Alvarez 1995a, b; Tait et al. 2011). In the Lindian basin, the Ituri Group consists of a basal clastic sequence containing conglomerates and sandstones, overlain by thick oolitic limestones and dolomites. Above it, the Lokoma and Aruwimi Groups are predominantly clastic (Verbeek 1970; Poidevin 2007). In both the Katangan and Zambian basins, the Roan Group (880–750 Ma) consists of a basal conglomerate, siliciclastics and carbonates (mainly dolomites and dolomitic shales) that unconformably overly Mesoproterozoic Kibaran formations (Cailteux et al. 2005;

Batumike et al. 2006; El Desouky et al. 2008). The Roan Group is overlain by the predominantly clastic and volcano- sedimentary rocks of the Mwashya the Nguba Groups (750–620 Ma). The latter contain a basal tillite known as the “ Grand Conglomerat ” (Lepersonne 1974), overlain by a thick carbonate sequence including limestones, dolomites, shales, dolomitic shales and interbbeded silts and sandstones (Cailteux et al. 2005; Batumike et al. 2007). The overlying Kundelungu molasses-like sequence (620–570 Ma) starts with a second glacial horizon, known as “ Petit Conglomerat ” (Lepersonne 1974).

6.2.2 RedBeds and the Transition Between the Neoproterozoic and Paleozoic

Throughout Central Africa, the transition between the upper Neoproterozoic and the earliest Paleozoic sedimentary sequences is poorly constrained because the transition sequences are non-fossiliferous siliciclastic redbeds.

Throughout the CB and its surrounding basins, relatively thick sequences of lithologically similar red sandstones (known as the ‘ Redbeds ’ ) have long been correlated and

Fig. 6.1 (Continued) (a) Geological setting of the Congo Shield with the Congo Basin in its center, surrounded by Archean cratonic blocks and Proterozoic mobile belts. Rectangle shows contour of (b). (b) Geo- logical map of the Congo basin and surrounding marginal

Neoproterozoic basins with location of the 2 stratigraphic wells

(Samba and Dekese) and the two exploration wells (Mbandaka-1 and

Dekese-1), indicated by their initials


assigned to the late Precambrian (Cahen et al. 1960; Verbeek 1970; Lepersonne 1974), although some researchers recognized parts could also be early Paleozoic in age (Evrard 1957). Subsequently many authors have tried to define the Neoproterozoic-Paleozoic transition in the basins surrounding the CB on the basis rather of structural criteria in Katanga and West Congo; and on the basis of lithological correlations with the Lindian Supergroup (Kampunzu and Cailteux 1999; Porada and Berhorst 2000; Master et al.

2005; Tack et al. 2008; Tait et al. 2011).

In West-Congo and Katanga, where these Redbeds occur along the tectonic fronts of the West-Congo and Lufilian fold belts, and from there extend towards the CB into their foreland, structural relations with reference to a supra- regional late Pan-African unconformity have been used to distinguish the red sandstones as both pre- and post-dating Pan-African deformation. In the West-Congo belt, for exam- ple, the Pan-African deformation has been dated at 566 42 Ma, the age of metamorphism of a dolerite sill that intrudes the Haut Shiloango Subgroup and the Inkisi Subgroup redbeds (Alvarez 1999; Tack et al. 2001; Frimmel et al. 2006). The Inkisi Subgroup is therefore considered as of latest Neoproterozoic to early Paleozoic age (Alvarez et al. 1995c; Tack et al. 2008; Tait et al. 2011). Recently, Monie´ et al. (2012) determined that the West Congo belt of Angola underwent two main deformation events of amphib- olite grade at c. 540 and 490 Ma, followed by tectonically assisted exhumation.

Similarly, in the Katanga basin, the sub-horizontal siliciclastic sequences of the Biano (Plateaux) Subgroup (uppermost subgroup of the Kudelungu Group) discordantly overlie the folded Katanga units and are considered therefore to be post Pan-African in age (Batumike et al. 2007;

Kampunzu and Cailteux 1999). The Lufilian Arc formed during collision between the Congo and Kalahari Shields between 650 and 530 Ma, with deformation peaking at ca.

550 Ma (Porada 1989; Hanson et al. 1993; Kampunzu and Cailteux 1999; Porada and Berhorst 2000; John et al. 2004;

Frimmel et al. 2006). Detrital muscovites from the Biano Subgroup have a maximum Ar/Ar age of 573 5 Ma at the top of the Katanga Supergroup (Master et al. 2005), while the minimum age of the Biano Subgroup is estimated as younger than 540 Ma (Kampunzu and Cailteux 1999). This suggests that at least some of the Biano sequences may have been deposited during the Cambrian (Kipata 2013).

In the sub-horizontal intracratonic Lindian Supergroup along the northern margin of the CB, no clear angular dis- cordance has been observed within the Aruwimi Group, but the Banalia red sandstones that form the upper part of this group, have been correlated lithostratigraphically with the Inkisi Group in West-Congo and the Biano (Plateaux) Sub- group in Katanga (Alvarez et al. 1995; Tack et al. 2008; Tait et al. 2011), but there are no direct age constraints.

Clearly throughout the Congo Shield, robust correlations between RedBeds sequences require more precise chronostratigraphy.

6.3 Structure and Stratigraphy of the Deep CB Based on Geophysics and Well Data

Since most of the CB is not accessible to direct observations, geophysical investigations can complement the surface geo- logy observations described above. Here we summarise Fig. 6.2 (a) Seismic-stratigraphy of sequence on a section of seismic profile R5, showing six depositional sequences, two unconformities and the calibrated trace of Mbandaka-1 well as identified in this chapter.

TWT: Two Way Travel-time (TWT in seconds). Vertical black line:

position of the well, red crosses: base of the seismic sequences

(corresponding depth in Table 6.2a). CDP 2231: Common Depth

Point location. (b) Time–Depth curve obtained from the CDP location

2231 along line R05, near the Mbandaka-1 projected trace well. The

curve shows the bottom limit of the different seismic sequences and the

well TD (4,350 m). Crosses: CDP data from Table 6.1a. The

depth–time curve was constructed by a polynomial interpolation of

the CDP data. Empty squares: depth–time plot of the base of the

seismic sequences from data of Table 6.2a


interpretations of the seismic and gravity data to further unravel the early history of the CB.

Whilst a distinct seismic reflector recognized below the CB has been interpreted to record Pan-African orogenesis (Daly et al. 1991, 1992; Kadima et al. 2011a), it only locally resolves a tectonic unconformity (for example on lines L50 and L51 in the centre of the basin; Figs. 6.3 and 6.4: marked as ‘ Lower unconformity ’ ). More often the reflector marks a conformable contact (see for example, line R5 calibrated against the Mbandaka-1 well; Fig. 6.2a).

6.3.1 Well Data

The original lithostratigraphic scheme of the central CB was established from logging the two fully cored stratigraphic wells: Samba and Dekese (Cahen et al 1959, 1960) and the two exploration wells: Mbandaka-1 and Gilson-1 (Esso Zaire 1981a, b) (location on Fig. 6.1). The Jurassic to Creta- ceous sequences that form the uppermost 700–1,200 m are relatively well described and dated by biostratigraphy (Colin 1994; Linol 2013; Linol et al., Chap. 8, this Book). Below, the Permo-Carboniferous sequences of the Lukuga Group were recognized in the Dekese well on the basis of their fossil plants and spores, and their glacial to peri-glacial characteristics. These were not encountered in the Samba well but suspected in the Mbandaka-1 and Gilson-1 wells. In the latter two deeper wells, these sequences overlie sili- clastics with dolomites (some with stromatolites) assigned to the Neoproterozoic, although the transition between the Precambrian and Paleozoic is poorly defined (see detailed lithostratigraphic subdivision of the four wells in Linol et al., Chap. 7, this Book). The Mbandaka-1 borehole stops at the depth of 4,350 m in a soft basement, interpreted to be halite (Esso Zaire 1981a).

6.3.2 Velocity Structure Based on Seismic Refraction Data

Evrard (1957) defined for the first time the P-wave velocity structure of the CB, based on the results of a refraction seismic survey calibrated with surface and well data at Samba and Dekese. Whilst Evrard (1957) stressed that this velocity structure is based on the physical characteristics of the sedimentary rocks and does not directly reflect the strati- graphy, the following synthesis seems robust: P-wave velo- cities < 3,600 m s


characterize the Mesozoic-Cenozoic sequences whilst velocities of ca. 3,900 m s


are typical for the middle to upper Paleozoic sequences. Higher velocities, between 4,200 and 4,600 m s


, likely represent the late Neoproterozoic to lower Paleozoic RedBeds, whilst

velocities > 5,000 m s


should represent the Neoprotero- zoic or older sediments and possibly crystalline basement.

6.3.3 Seismic-Stratigraphic Sequences

Using the seismic profiles acquired by Exxon-Texaco in 1974–1976 (location on Fig. 6.1), ECL (1988) and Daly et al. (1992) distinguished six seismic-stratigraphic sequences (or “ Supersequences ” ) above the acoustic crystal- line basement, each bounded by regional unconformities.

These sequences are re-described below (using the same numbering as in Daly et al. 1992) with reference to the seismic profile R5 shot along the Congo River and passing close to the Mbandaka-1 well (Figs. 6.1b, 2a). They are also illustrated on the land seismic profile L51 whose northern extremity approaches the Samba well (Figs. 6.1b, 3).

On the R5 profile (Fig. 6.2a), the depth-time curve is presented for CDP (Common Depth Point) location 2,231, measured closest to the Mbandaka-1 well (Fig. 6.2b). The depth-time curve was constructed by a polynomial interpo- lation of the CDP data (Table 6.1a). This allowed calculating the depth of the base of the different seismic-stratigraphic sequences and their thicknesses, as identified on the seismic line R5 (Table 6.2a). For reference, the bottom (TD) of the Mbandaka-1 well at 4,350 m deep correspond to a TWT time of 2,139 ms. Similarly, the depth to the base of the sequences identified on Line L51 have been calibrated for CDP 850 (Fig. 6.3, Tables 6.1a and 6.2b).

Except for the uppermost sequence (5), the ages of all sequences is poorly defined. Two major unconformities are identified and traced in most of the seismic profiles Fig. 6.3 Seismic stratigraphy of sequences identified on a section of profile L51 in the CB and linked further north to the Samba well (Fig. 6.1b) and two major unconformities as interpreted in this chapter.

The first four sequences beneath the lower unconformity are deformed

on the left (SW) side of the profile. TWT Two Way Travel-time ( in

seconds). Vertical black line: position of CDP 850, red crosses: base of

the seismic sequences (corresponding depth in Table 6.2b)


(relatively distant one from another). However their age control is also poor (especially for the lower one) and it is possible that there are more than 2 regional unconformities (e.g. Daly et al. 1992 identified 6 unconformities). Sequence 0

Along several profiles, a reflection-free seismic pattern that corresponds to the acoustic basement is interpreted to represents crystalline basement. The latter is overlain by a low-amplitude, discontinuous and transparent seismic patterns forming the first sequence (Sequence 0 of Daly et al. 1992). The reflectors diverge towards the centre of the CB, suggesting tilting during deposition; and the sequence is thicker in the centre of the basin than at its border. Sequence 0 is apparently discontinuous, with rapid variations in thickness and its base generally is not well- imaged. Sequence 0 was not penetrated by any cored wells.

It could represent siliciclastic sediments (essentially con- glomeratic) if correlated with the Liki-Bembian Group out- cropping to the NW of the basin (e.g. Daly et al. 1992) and may thus represents the basal Precambrian sedimentary unit of the CB. Alternatively, it may also be correlated with the lower Neoproterozoic clastic sequence (BI) of the Mbuji-Mayi basin (Delpomdor et al. 2013a, b; and Chap. 4, this Book) and the Roan Group of the Katangan and Zambian basins.

The base of sequence 0 is not identified in the R05 seismic profile, but suspected in profile L51, at ~ TWT 3,710 ms, which is calibrated using the CDP 850 data at ~9,400 m depth, for a thickness of ~ 1,100 m (Fig. 6.3;

Tables 6.2a, b). Sequence 1

Sequence 1 has a layered seismic pattern characterized by highly continuous and divergent reflectors. In the Mbandaka-1 well its top occurs at ca. 3,960 m, and its bottom at 4,350 m. From this bottom upward to 4,133 m depth, the sequence is represented by a 217 m thick succes- sion of dark-grey calcareous silty shales that grade into argillaceous and dolomitic limestones, with interbedded salt crystals and sparse anhydrite at the base (Esso Zaire 1981a). In the Gilson-1 well, it is represented between 4,503 m depth and the bottom of the well (4,665 m) by alternating beds of sandstone, siltstone, shale and dolomite, with massive dolomite at the base (Esso Zaire 1981b). Sequence 1 is correlated with the Ituri carbonates of the Lindian Supergroup of Verbeek (1970) and represents the M9 sequence of Linol (2013) in the Mbandaka-1 well, and the G10 sequence of Linol (2013) in the Gilson-1 well. It could possibly be correlated also with the carbonate sequence (BII) of the Mbuji-Mayi basin (Delpomdor et al. 2013a, b). Using the CDP 2231 data, its thickness at the position of the Mbandaka-1 well would be ~ 670 m. In profile L51, at CDP 850, Sequence 1 is ~1,220 m thick with its base at a depth of ~ 8,290 m (Fig. 6.3, Table 6.2b). Sequence 2

A second transparent seismic pattern with discontinuous reflectors and one or two strong to medium continuous reflectors in the middle overlies Sequence 1. In the R5 profile (Fig. 6.2a, b; Table 6.2b), it corresponds to an interval Table 6.1 CPD data

(a) For location 2231 along the line R5, close to the Mbandaka-1 well

Times (ms) 1 316 601 691 1,058 1,555 2,041 2,500 5,000

VRMS (m/s) 1,756 1,859 2,085 2,345 3,282 3,865 4,133 4,555 8,000

Depth (m) 1 294 623 786 1,621 2,824 4,023 5,422 15,000

(b) Location 850 along line R51

Times (ms) 0 625 750 1,050 1,450 1,850 2,225 2,975 5,000

VRMS (m/s) 2,000 2,500 2,690 3,145 3,565 4,075 4,480 4,950 6,000

Depth (m) 0 701 999 1,609 2,506 3,615 4,758 7,059 14,422

Table 6.2 Depth for the base of seismic sequences and their thickness, obtained after calibration using the CDP data (a) Location 2231 along the line R5, close to the Mbandaka-1 well

Seismic sequences 5 4 3 2 1 0

Depth (m) 877 2,270 2,844 3,960 4,350


Thickness (m) 877 1,393 370 1,320 390


(b) Location 850 along line R51

Seismic sequences 5 4 3 2 1 0

Depth (m) 1,120 2,990 5,410 7,070 8,290 9,400

Thickness (m) 1,120 1,770 2,420 1,660 1,220 1,210


Base of the sequence No defined


between 2,644 m and 3,960 m depth (1,316 m thick). It also broadly corresponds to conglomeratic and sandstone sequences M9 and M8 of Linol (2013). The transparent character is well seen in the seismic profile R51 (Fig. 6.3), where at CDP 850, it is ca. 1,660 m thick and its base is at ca.

7,070 m deep (Table 6.2b). Sequence 3

Sequence 3 has a banded seismic pattern characterized by slightly divergent and strongly to moderately continuous reflectors. An angular unconformity observed along the deformed part of the basin constitutes the upper boundary of the sequence, which defines the lower major regional unconformity and can be detected on most of the seismic profiles (Daly et al. 1992; Kadima 2011; Kadima et al.

2011a, b). The angular character of this unconformity is well defined in the southern part of profile L51 (Fig. 6.3), and in the central part of profile L50 (Fig. 6.4). In profile R5 (Fig. 6.2a), it appears as a conformable contact and is there- fore more difficult to identify. In the R5 profile, at the location of the Mbandaka-1 well, Sequence 3 appears between ~2,270 and ~2,640 m deep (Table 6.2) and is correlated in the Mbandaka-1 well with the red-orange conglomerates of the M7 sequence of Linol (2013). This sequence is observed in line L51 at the position of CDP 850, between ~5,410 and ~2,990 m (~2,420 m thick; Table 6.2b).

We tentatively correlate this Sequence 3, together with the underlying Sequence 2, with similar (predominantly clastic) sequences in the marginal basins: the molassic Mpioka Group in West Congo (Frimmel et al. 2006), the predominatly clastic Kundelungu and Nguba Groups in the Katanga basin (Cailteux et al. 2007), and the dominantly clastic Aruwimi Group in the Lindian basin (Verbeek 1970). Sequence 4

Overlying the lower regional unconformity, a parallel to subparallel seismic pattern marked by moderate to low con- tinuous reflectors constitutes the fifth sequence (e.g.

Sequence 4 of Daly et al. 1992). Its upper boundary is another angular unconformity that constitutes the second (or upper) regional unconformity in the CB. Well logs show that Sequence 4 is mostly siliciclastic, comprising red sandstones and conglomerates. According to the inter- pretation of seismic profile R5 (Fig. 6.2a), this sequence is 1,390 m thick in the region of the Mbandaka-1 well, between depths ca. 877 m and ca. 2,270 m. It corresponds to the M5 and M6 sequences of Linol (2013, and assigned to the Triassic). On CDP 850 along line 51, it is ca. 1,870 m thick, between ca. 1,120 m and ca. 2,990 m deep. Sequence 5

The sixth and youngest seismic sequence (Sequence 5) consists of parallel highly continuous reflectors grading upwards to wavy moderate to strong reflectors. The lower boundary of this sequence corresponds to the upper regional unconformity as defined above. Well logs and outcrop data show that it contains essentially continental clastic formations ranging in age from the Late Jurassic to the Neogene. It appears undeformed on the seismic profiles and has a rela- tively constant thickness over the entire CB: 715 m at Dekese (Cahen et al. 1960), 1,167 m at Samba (Cahen et al. 1959), 844 m at Mbandaka and 998 m at Gilson (Esso Zaire 1981a;

Linol 2013), and ~1,120 m thick along line L51 at CDP 850.

To directly compare their seismic-stratigraphic interpretations of the CB, Kadima et al. (2011a) regroup the first four sequences of Daly et al. (1992) into a lower seismic unit (Unit A), contained beneath the lower major unconformity. This Unit A is locally affected by tectonic deformation. By correlation with the depocenters surrounding the CB and considering that this lower uncon- formity could represent the end of Pan-African deformation, the seismic Unit A likely represents the equivalent the Neoproterozoic sedimentary sequences flanking the CB.

Sequence 4, which is bound between the two regional unconformities, is named seismic Unit B, and possibly represents the Paleozoic and early Mesozoic (e.g. Triassic;

see below). In this scheme, the uppermost seismic Unit C would represent the Jurassic-Cretaceous and Cenozoic.

6.3.4 Tectonism

The Neoproterozic sequences of the seismic Unit A as defined above have been affected by Pan-African defor- mation. Some of those structures apparently have been reactivated also by late Paleozoic-early Mesozoic deformations. In contrast, the lower-middle Paleozoic red Fig. 6.4 Seismic stratigraphy and structural interpretation of N–S

seismic line L50 in the center (Fig. 6.1b). The lower unconformity

has been deformed during or after deposition of Sequence 5 by reacti-

vation of underlying structures. Yellow line: folded and faulted reflector

at the base of strongly reflecting sequence 2. TWT Two Way Traveltime



sandstones at the base of Unit B, together with the overlying Carboniferous-Permian diamictites and black shales, have been deformed only by the late Paleozoic-early Mesozoic deformation. This is well illustrated by the N-trending seis- mic profile L50 in the centre of the basin (Fig. 6.4) by structures such as flexures, anticlines, synclines and thrust faults, although it would be difficult to distinguish these from syn-depositional features related to slumping and gla- cial processes, or even salt tectonics. The first deformation event occurred prior to the deposition Sequence 4 and the second affects it, mainly by reactivating the structures underlying the lower unconformity. Each deformation event is characterized by an erosional phase followed by renewed sedimentation with by top-lap structures. These deformational events are interpreted as representing intra- plate compressional tectonic episodes related to far-field tectonic stresses generated by Pan African collisional tec- tonics flanking the margin of the Congo Shield for the first event, and at the margin of Gondwana (during the formation of the Cape Fold Belt at ca. 250 Ma) for the second one (e.g.

Daly et al. 1992; Kadima et al. 2011a; Kipata et al. 2013.

However, if the Sequence 4 also includes the Triassic, then the second deformation would be post-Triassic and therefore cannot be related to the Cape Fold Belt and would require a different interpretation of the far field stresses (Linol 2013;

see also Linol et al., Chap. 11, this Book).

6.3.5 Gravity Anomalies and Modelling

The CB is associated with a large-scale and pronounced negative free-air gravity anomaly (Jones et al. 1960;

Sandwell and Smith 1997; Tapley et al. 2005). Initiation of the CB is frequently related to the development of a NW–SE Neoproterozoic rift and a large part of its subsequent subsi- dence to post-rift thermal relaxation (e.g. Kadima et al.

2011a, b; Buiter et al. 2012).

The large scale and amplitude of the gravity anomaly has led various researchers of the CB to propose very different geodynamic models to account for subsidence of the CB.

Hartley and Allen (1994) and Hartley et al. (1996), for example, suggested the negative Bouguer gravity could be due to the combined effect of lower density sediments in the basin and higher density material in the lithospheric mantle to isostatically compensate for the sediments; and indeed, Downey and Gurnis (2009) show numerically that the topog- raphy and negative free-air gravity data over the basin can be explained by a high-density body within the deeper lithosphere.

By contrast, Heine et al. (2008), suggested that subsi- dence might be due to dynamic topography, consistent with Sahagian (1993) and Burke and Gunnell (2008), who prefer models in which the CB acquired its modern shape through mantle (plume) driven uplift of swells surrounding the basin.

Others prefer a model in which recent subsidence of the CB is controlled by a late phase of the ca. 700 Ma post-rift thermal subsidence following the Neoproterozoic extension (e.g. Armitage and Allen 2010; Crosby et al. 2010; Kadima et al. 2011b), while Buiter et al. (2012) suggests that the observed negative gravity anomaly across the CB is mainly due to the thick (up to 9 km) sedimentary units in the basin, and that the sub-lithospheric mantle structures did not appar- ently play a role in the recent subsidence of the basin.

To further test a simple long lived thermal history for the CB, Kadima et al. (2011b) backstripped the effects of the CB sediments and noted a residual NW–SE positive and narrow gravity anomaly across the central CB, which they interpreted as the remaining crustal thinning associated with the Neoproterozoic rift that initiated the CB. The paleo-rift is aligned along the Mbandaka-1 and Dekese posi- tive Bouguer anomalies of Jones et al. (1960) and Kadima et al. (2011a). Assuming that isostasy is governed by crustal necking and flexural response to sediment loads, Kadima et al. (2011b) obtained a best fit to the residual gravity with a necking depth of 10 km and an equivalent lithospheric elastic thickness of 100 km. Consequently, the linear anom- aly is interpreted as an old tectono-thermal heritage of the initial Neoproterozoic rifting, when denser mantle associ- ated with Moho uplift invaded the necking zone and has remained in place ever since (Kadima et al. 2011b). 2D coupled gravity and magnetic models were constructed across this elongated NW-trending positive residual ano- maly, along the seismic lines constrained by well data, to test the hypothesis for a rifting process with extensional magmatism activity prior to the basin formation (Kadima et al. 2011a). The main results are as follows:

• Modeling of two SW–NE profiles, one along the Congo River and passing close to the Mbandaka-1 well and one passing through the Dekese well is consistent with a lateral change in basement density along the trend of the profile, suggesting that the elongate positive NE-tending residual gravity anomaly zone could correspond to a deep crustal discontinuity injected by mafic magma during the Neoproterozoic rifting.

• The modelling is also consistent with (but does not prove)

the presence of evaporite sequences in some of the deeper

units in lateral continuity with evaporite showings


observed at the bottom of the Mbandaka-1 and Gilson-1 wells. The modelled low susceptibility values of some layers suggest that they could contain a significant pro- portion of salt.

• The poorly defined seismic facies that led to the previous interpretations of crystalline basement uplift is shown to be also consistent with paleo-salt tectonics.

6.4 Discussion

The Neoproterozoic period in Central Africa was marked by crustal extension with the opening of rift basins during the initial development of the CB near the centre of the Congo Shield. This was accompanied by the formation and preser- vation of Neoproterozoic basins surrounding the CB. Litho- stratigraphic, structural, and paleo-environmental similarities have been established between all these basins (Tait et al.

2011; Delpomdor 2013; Delpomdor et al., Chap. 4, this Book). The sediments were subsequently affected by com- pressional tectonics related to the Pan African and late Paleozoic-early Mesozoic orogens.

The data discussed here suggest to us rather that the Neoproterozoic CB was initiated during an intracratonic rifting process, possibly related to the break-up of the Rodinia Supercontinent. Such extensional setting may also have initiated the development of the other Neoproterozoic basins now preserved along the periphery of the Congo Shield. Mafic magmatism associated with this regional rifting event is observed in the West Congo, Sembe´-Ouesso, Bangui, Fouroumbala-Bakouma, Itombwe, Malagarazi- Bukoban, Roan, Kundelungu and Mbuji-Mayi basins (Tack et al. 2001, 2010; Vicat et al. 1989; Hanson et al. 1994;

Johnson et al. 2005; Key et al. 2001; Kampunzu and Cailteux 1999; Batumike et al. 2009; Delpomdor et al.

2013b). Within the CB, there is no evidence to confirm or exclude similar magmatic activity, but 2-D modelling suggests that a linear NW-SE positive residual gravity anomaly in the centre of the basin may be associated with mafic intrusions into the crustal basement. Both Evrard (1957) and Kadima et al. (2011a, b) attributed the short wavelength gravity anomalies observed near Dekese and Mbandaka-1 to such intrusions into the upper crust.

The lithostratigraphic successions in all the Neoprotero- zoic basins developed across the Congo Shield show first- order similarities, with in their lower parts carbonate-rich sediments overlain by siliciclastic sequences that include tillites (for more details see Delpomdor et al., Chap. 4, and de Wit and Linol, Chap. 2, this Book). In most of the peripheral basins, the carbonate units overlie a basal con- glomeratic sequence. As shown by the deep well logs (Esso Zaire 1981a, b) and previous seismic analysis, the deepest part of the CB may contain similar units. A massive

carbonate formation with evaporite showings (the “ carbon- ate-evaporite ” sequence of ECL 1988; Lawrence and Makazu 1988; Daly et al. 1992), was reported from the lower Mbandaka-1 well and defined as Sequence 1 (670–1,200 thick). The carbonates are considered as late Neoproterozoic, Ediacaran-Cryogenian (e.g. Daly et al.

1992; Kadima et al. 2011a; Linol 2013; Delpomdor, et al., Chap. 4, this Book) by lithostratigraphic correlation with and between the outcropping sequences of carbonates in the peripheral basins. Beneath this carbonate unit, the basal siliclastic sequence (Sequence 0) tends to thicken towards the centre of the CB (to up to ca. 1,100 m). Overlying the carbonate unit is a predominance of siliciclastic sequences with intercalation of thin carbonate layers, defined in the two deep exploration wells and in the seismic profiles as Sequences 2 and 3 (1,700 to 4,100 m), and here attributed to the late Neoproterozoic-early Paleozoic.

In the marginal West Congo, Lindian and Katangan basins, recent observations suggest that the uppermost clas- tic sequences (the Inkisi, Biano and Banalia Groups) are not affected by Pan-African deformations and therefore may be early- to mid-Paleozoic in age (Alvarez et al. 1995; Master et al. 2005; Batumike et al. 2006; Tack et al. 2008;

Kampunzu and Cailteux 1999; Kampunzu et al. 2009;

Cailteux et al. 2007; Tait et al. 2011).

In the CB, seismic Sequences 1 to 4 have been locally affected by a compressional tectonism event responsible for inversion structures such as folds and thrusts (Daly et al. 1992 and Kadima et al. 2011a). An erosional unconformity separates Sequence 4 from Sequence 5. We consider that the first four sequences form the late Neoproterozoic-early Paleo- zoic sedimentary record of the CB, with the lower major erosional surface represented by a Pan African unconformity.


A series of basins formed in Central Africa at the periph- ery of the Congo Shield and the large CB formed near its centre during the early Neoproterozoic by rifting and mafic magmatism related to the break-up of Rodinia.

The early phase of the CB developed during this time

along a NW-SE elongated structure corresponding to the

Mbandaka-Dekese axis, intruded by mafic material that

locally densified the crust; and was filled subsequently by

up to 9 km of Neoproterozoic to Cenozoic sediments

following long term (ca. 700 million years) thermal- and

density-driven subsidence. Indirect observations suggest

that the first seismic-stratigraphic sequence in the CB

(Sequence 0) may consist of syn-rift clastics, with slightly

divergent reflectors, followed by the deposition of

carbonates, with an undetermined amount of evaporites

(Sequence 1), and then two siliciclastic sequences with

thin carbonate layers and tillites interbedded (Sequences

2 and 3). These four sequences are grouped in the seismic


Unit A of Kadima et al. (2011a), which is more than 2,360 m thick in the Mbandaka-1 well and up to 6,400 m thick along Line L51. They all have been affected by contractional deformation interpreted to be related to Pan-African orogenesis, causing basin inver- sion. They are therefore considered as of pre- to syn- tectonic relative to this event and are thus of Neoproterozoic age.

A regional unconformity truncates these structures and forms the base of Sequence 4 (1,400–1,900 m thick). This sequence comprises undated red sandstones at the base, followed by glacial to peri-glacial sediments of Late Carboniferous—Permian age. It is delineated at the top by a second regional tectonic unconformity and forms the seismic Unit B of Kadima et al. (2011a). This unit is less deformed than the four deeper sequences, and mainly by the reactivation of earlier structures in Unit A. The overlying Sequence 5 (Seismic Unit C of Kadima et al.

2011a) contains essentially continental formations attributed to the Upper Jurassic-Cenozoic and is between 800 m to 1,200 m thick.

Acknowledgements This work was supported by the Frame Agree- ment program MRAC-DGCD under project S1_RDC_Geodyn_- UNILU. E. Kadima and S. Sebagenzi gratefully acknowledge this program and the Royal Museum for Central Africa for coordinating this project. C. Blanpied is thanked for further discussion on the interpretation of seismic profiles. M. de Wit and B. Linol are thanked for the critical review of several versions of this Ms.


Alvarez P (1995a) Les facteurs de controˆle de la se´dimentation du Supergroupe Ouest-congolien (Sud-Congo). Rampe carbonate´e et activite´ biologique au Prote´rozoı¨que supe´rieur. Implication en Afrique centrale (Congo, Zaı¨re, Gabon, Cameroun, Guine´e Equatoriale, Centrafrique). Document BRGM, 239, 273 p Alvarez P (1995b) Evidence for a Neoproterozoic carbonate ramp on

the northern edge of the Central African Craton: relations with Late Proterozoic intracratonic troughs. Geol Rund 84:636–648 Alvarez P, Maurin J-C, Vicat J-P (1995) La Formation de l ’ Inkisi

(Supergroupe Ouest-congolien) en Afrique centrale (Congo et Bas-Zaı¨re): un delta d ’ aˆge Pale´ozoı¨que comblant un bassin en extension. J Afr Earth Sci 20:119–131

Alvarez P (1999) La transition Pre´cambrien-Cambrien en Afrique Centrale. Approche inte´gre´e: Pale´oenvironnements et donne´es pale´ontologiques. Habilitation a` diriger des recherches. Universite´

de Poitiers, 1999, 307 p

Armitage JJ, Allen PA (2010) Cratonic basins and the long-term subsi- dence history of continental interiors. J Geol Soc London 167:


Armstrong RA, Master S, Robb LJ (2005) Geochronology of the Nchanga Granite and constraints on the maximum age of the Katanga Supergroup, Zambian Copperbelt. J Afr Earth Sci 42:


Batumike MJ, Cailteux JLH, Kampunzu AB (2007) Lithostratigraphy, basin development, base metal deposits, and regional correlations of

the Neoproterozoic Nguba and Kundelungu rock successions, cen- tral African Copperbelt. Gondwana Res 11(3):432–447

Batumike J, Griffin W, O’Reilly SY, Belousova EA, Pawlitschek M (2009) Crustal evolution in the central Congo-Kasaı¨ Craton, Luebo, D.R. Congo: insights from zircon U-Pb ages, Hf-isotope and trace- element data. Precambrian Res 170(1–2):107–115

Batumike MJ, Kampunzu AB, Cailteux J (2006) Petrology and geo- chemistry of the Neoproterozoic Nguba and Kundelungu Groups, Katangan Supergroup, southeast Congo: implications for prove- nance, paleoweathering and geotectonic setting. J Afr Earth Sci 44:97–115

Buiter SJH, Steinberger B, Medvedev S, Tetreault JL (2012) Could the mantle have caused subsidence of the Congo Basin? Tectono- physics 514–517:62–82

Burke K, Gunnell Y (2008) The African erosion surface: a continental- scale synthesis of geomorphology, tectonics, and environmental change over the past 180 million years. Geol Soc Am Mem 201 Cahen L (1954) Ge´ologie du Congo belge. Vaillant-Caramanne, Lie`ge,


Cahen L, Ferrand JJ, Haarsma MJF, Lepersonne J, Verbeek Th (1959) Description du Sondage de Samba. Ann. Mus. Roy. Congo belge, Tervuren (Belgique), se´rie in-8, Sci Ge´ol 29, 210 pp

Cahen L, Ferrand JJ, Haarsma MJF, Lepersonne J, Verbeek Th (1960) Description du Sondage de Dekese. Ann. Mus. Roy. Congo belge, Tervuren (Belgique), se´rie in-8, Sci Ge´ol 34, 115 pp

Cahen L, Snelling NJ, Delhal J, Vail JR, Bonhomme M, Ledent D (1984) Geochronology and evolution of Africa. Clarendon, Oxford, 512 p Cailteux J (1994) Lithostratigraphy of the Neoproterozoic Shaba-type

(Zaı¨re) Roan Supergroup and metallogenesis of associated strati- form mineralisation. J Afr Earth Sci 19:279–301

Cailteux J, Kampunzu AB, Lerouge C, Kaputo AK, Milesi JP (2005) Genesis of sediment-hosted stratiform copper-cobalt deposits, Central African Copperbelt. J Afr Earth Sci 42:134–158

Cailteux J, Kampunzu AB, Lerouge C (2007) The Neoproterozoic Mwashya-Kasuki sedimentary rock succession in the central Afri- can copperbelt, its Cu-Co mineralisation, and regional correlations.

Gondwana Res 11:414–431

Colin JP (1994) Mesozoic-Cenozoic lacustrine sediments of the Zaı¨re Interior Basin. In: Gierlowski-Kordesch E, Kelts K (eds) Global geological record of lake basins, vol 1. Cambridge University Press, pp 31–36

Crosby AG, Fishwick S, White N (2010) Structure and evolution of the intracratonic Congo Basin. Geochem Geophys Geosyst 11: Q06010 Daly MC, Lawrence SR, Diemu-Tshiband K, Matouana B (1992) Tectonic evolution of the Cuvette Centrale, Zaire. J Geol Soc London 149:539–546

Daly MC, Lawrence SR, Kimun ’ a D, Binga M (1991) Late Paleozoic deformation in central Africa: a result of distant collision? Nature 350:605–607

Deblond A, Punzalan LE, Boven A, Tack L (2001) The Malagarazi supergroup of southeast Burundi and its correlative Bukoba super- group of northwest Tazania: Neo- and Meso-proterozoic constraints from Ar-Ar ages of mafic intrusive rocks. J Afr Earth Sci 32:


Delpomdor F (2013) Sedimentology, geochemistry and depositional

environments of the 1175-570 Ma carbonate series, Sankuru-

Mbuji-Mayi-Lomami-Lovoy and Bas-Congo basins, Democratic

Republic of Congo - New insights into Late Mesoproterozoic and

Neoproterozoic glacially- and/or tectonically-influenced sedimen-

tary systems in equatorial Africa. PhD thesis, ULB, Brussels, 497 p

Delpomdor F, Blanpied C, Virgone A, Pre´at A (2013a) Paleo-

environments in Meso-Neoproterozoic carbonates of the Mbuji-

Mayi Supergroup (Democratic Republic of Congo) - Microfacies

analysis combined with C-O-Sr isotopes, major-trace elements and

REE+Y distributions. J Afr Earth Sci 88:72–100


Delpomdor F, Linnemann U, Boven A, Ga¨rtner A, Travin A, Blanpied C, Virgone A, Jelsma H, Pre´at A (2013b) Depositional age, prove- nance, and tectonic and paleoclimatic settings of the late Mesoproterozoic–middle Neoproterozoic Mbuji-Mayi Supergroup, Democratic Republic of Congo. Palaeogeogr Palaeoclimatol Palaeoecol 389:35–47

Delpomdor F, Kant F, Pre´at A (2014) Neoproterozoic uppermost Haut- Shiloango Subgroup (West Congo Supergroup, Democratic Repub- lic of Congo): Misinterpreted stromatolites and implications for sea- level fluctuations before the onset of the Marinoan glaciation. J Afr Earth Sci 90:49–63

De Paepe P, Tack L, Moens L, van de Velde P (1991) The basic magmatism of upper Proterozoic in southeast Burundi. Muse´e royal de l’Afrique Centrale, Tervuren, Belgique, rapport annuel 1989–1990:85–104

De Waele B, Johnson SP, Pisarevsky SA (2008) Paleoproterozoic to Neoproterozoic growth and evolution of the eastern Congo Craton:

its role in the Rodinia puzzle. Precambrian Res 160:127–141 Downey NJ, Gurnis M (2009) Instantaneous dynamics of the cratonic

Congo Basin. J Geophys Res Solid Earth 114, B06401

ECL (1988) Hydrocarbon potential of Cuvette Centrale (Republic of Zaire). Exploration Consultants Limited, Cellule Technique Pe´trolie`re, Pe´trozaire, unpublished report, 41pp. + figures, tables, appendices and enclosures.

El Desouky HA, Muchez P, Dewaele S, Boutwooe A, Tyler R (2008) Postorogenic Origin of the Stratiform Cu Mineralization at Lufukwe, Lufilian Foreland, Democratic Republic of Congo. Econ Geol 103:555–582

Esso Zaire SARL (1981a) Geological completion report. Mbandaka-1.

Unpublished internal report

Esso Zaire SARL (1981b) Geological completion report. Gilson-1.

Unpublished internal report

Evrard P (1957) Les recherches ge´ophysiques et ge´ologiques et les travaux de sondage dans la Cuvette congolaise. Acade´mie Royale des Sciences Coloniale., Sc. Techn. Bruxelles, VII(1), 62 p Evrard P (1960) Sismique. (Re´sultat scientifique des missions du

Syndicat pour l ’ e´tude ge´ologique et minie`re de Cuvette congolaise).

Ann Mus royal Afrique centrale, Tervuren (Belgique), se´rie in-8, Sci Ge´ol, 33, 87 p

Frimmel H, Tack L, Basei M, Nutman A, Boven A (2006) Provenance and chemostratigraphy of the Neoproterozoic West Congolian Group in the Democratic Republic of Congo. J Afr Earth Sci 46:


Hanson RE, Wardlaw MS, Wilson TJ, Mwale G (1993) U-Pb zircon ages from the Hook granite massif and Mwembeshi dislocation:

constraints on Pan-African deformation, plutonism, and trans- current shearing in central Zambia. Precambrian Res 63:189–206 Hanson RE, Wilson TJ, Munyanyiwa H (1994) Geologic evolution of

the Neoproterozoic Zambezi orogenic belt in Zambia. J Afr Earth Sci 18:135–150

Hartley RW, Allen PA (1994) Interior cratonic basins of Africa: rela- tion to continental break-up and role of mantle convection.

Basin Res 6:95–113

Hartley R, Watts AB, Fairhead JD (1996) Isostasy of Africa.

Earth Planet Sci Lett 137:1–18

Heine C, Mu¨ller RD, Steinberger B, Torsvik TH (2008) Subsidence in intracontinental basins due to dynamic topography. Physics of the Earth and Planetary interoirs. Recent advances in computational geodynamics: theory. Num Appl 1–4:252–264

John T, Schenk V, Mezger K, Tembo F (2004) Timing and PT evolu- tion of whiteschist metamorphism in the Lufilian Arc - Zambezi belt orogen (Zambia): implications for the assembly of Gondwana.

J Geol 112:71–90

Johnson SP, Rivers T, De Waele B (2005) A review of the Meso- proterozoic to Early Paleozoic magmatic and tectonothermal

history of Central Southern Africa: Implications for Rodinia and Gondwana. J Geol Soc London 162:433–450

Johnson SP, De Waele B, Tembo F, Evans D, Iizuka T, Tani K (2007) Geochronology of the Zambezi Supracrustal sequence, southern Zambia: a record of Neoproterozoic divergent processes along the southern margin of the Congo Craton. J Geol 115:355–374 Jones L, Mathieu PL, Strenger H (1960) Gravime´trie: Les re´sultats

scientifiques des missions du syndicat pour l’e´tude ge´ologique et minie`re de la Cuvette Congolaise et travaux connexes. Ann. Mus.

Roy. Congo belge, Tervuren (Belgique), se´rie in-8, Sci Ge´ol, 36, 46 pp

Kadima EK (2011) Contribution ge´ophysique a` la connaissance du bassin de la Cuvette congolaise. Mode´lisation de la structure se´dimentaire, Me´canisme de subsidence et structure de la litho- sphe`re sous-jacente. PhD thesis, University of Lubumbashi, 278 p Kadima E, Delvaux D, Sebagenzi MN, Tack L, Kabeya M (2011a)

Structure and geological history of the Congo Basin: an integrated interpretation of gravity, magnetic and reflection seismic data.

Basin Res 23:499–527

Kadima EK, Sebagenzi SMN, Lucazeau F (2011b) A Proterozoic-rift origin for the structure and evolution of the cratonic Congo Basin.

Earth Planet Sci Lett 304:240–250

Kampunzu AB, Cailteux J (1999) Tectonic evolution of the Lufilian Arc during Neoproterozoic Pan African orogenesis. Gondwana Res 2:401–421

Kampunzu AB, Tembo F, Matheis G, Kapenda D, Huntsman-Mapila P (2009) Geochemistry and tectonic setting of mafic igneous units in the Neoproterozoic Katangan Basin, Central Africa: implication for Rodinia break up. Gondwana Res 3:125–153

Key RM, Liyungu AK, Njamu FM, Somwe V, Banda J, Mosley PN, Armstrong RA (2001) The western arm of the Lufilian Arc in NW Zambia and its potential for copper mineralisation. J Afr Earth Sci 33(3/4):503–528

Kipata ML (2013) Brittle tectonics in the Lufilian foldand-thrust belt and its foreland. An insight into the stress field record in relation to moving plates (Katanga, DRC). PhD Thesis, KULeuven, 130 p Kipata ML, Delvaux D, Sebagenzi MN, Cailteux J-J, Sintubin M

(2013) Brittle tectonic and stress field evolution in the Pan-African Lufilian arc and its foreland (Katanga, DRC): from orogenic com- pression to extensional collapse, transpressional inversion and tran- sition to rifting. Geol Belg 16(1–2):001–017

Lawrence SR, Makazu MM (1988) Zaire ’ s Central basin: prospectivity outlook. Oil Gas J 86(38):105–108

Lepersonne J (1974) Carte ge´ologique du Zaı¨re au 1/2.000.000 et notice explicative. Re´publique du Zaı¨re, Direction de la Ge´ologie, Kinshasa & Mus. Roy. Afr. Centr., Tervuren

Linol B (2013) Sedimentology and sequence stratigraphy of the Congo and Kalahari basins of South-Central Africa and their evolution during the formation and breakup of West-Gondwana.

PhD thesis Nelson Mandela Metropolitan University, South Africa, 370 p

Master S, Rainaud C, Armstrong RA, Phillips D, Robb LJ (2005) Provenances ages of the Neoproterozoic Katanga Supergroup (Cen- tral African Copperbelt), with implications for basin evolution.

J Afr Earth Sci 42:41–60

Monie´ P, Bosch D, Bruguier O, Vauchez A, Rolland Y, Nsungani P, Buta Neto A (2012) The Late Neoproterozoic/Early Palaeozoic evolution of the West Congo Belt of NW Angola: geochronological (U-Pb and Ar-Ar) and petrostructural constraints. Terra Nova 24:238–247. doi:10.1111/j.1365-3121.2012.01060

Pe´rez-Gussinye´ M, Metois M, Fernandez M, Verge´s J, Fullea J, Lowry A (2009) Effective elastic thickness of Africa and its relationship to other proxis for lithospheric structure and surface tectonics.

Earth Planet Sci Lett 287:152–167


Poidevin J-L (1976) Les formations du Pre´cambrien supe´rieur de la re´gion de Bangui (R.C.A.). Bulletin de la Socie´te´ Ge´ologique de France 18(4):999–1003

Poidevin J-L (1979) Les basaltes et dole´rites Pre´cambrien supe´rieur de la re´gion de Bakouma (Empire centrafricain) 7e`me Re´union Annuelle des Sciences de la Terre., Lyon, 374

Poidevin J-L (1985) Le Prote´rozoı¨que supe´rieur de la Re´publique Centrafricaine. Ann. Mus. royal Afrique centrale, Tervuren (Belgique), se´rie in-8, Sci Ge´ol, 91, 75p.

Poidevin J-L, Alabert J, et Miauton J-D (1980/1981) Geologie des series du Precambrien superieur de la region de Bakouma (Republique Centrafricaine). Bull. BRGM (2eme ser.) IV(4):


Poidevin J-L (1996) Re´ponse. Un segment de rampe carbonatee d’age proterozoi’que supe´rieur au Nord du craton d’Afrique centrale (Sud-Est de la Republique centrafricaine). J Afr Earth Sci 23, 2 Poidevin J-L (2007) Stratigraphie isotopique du strontium et datations

des formations carbonate´es et glacioge´niques ne´oprote´rozoı¨ques du Nord et de l ’ Ouest du craton du Congo. Comptes Rendus Geo- science 339:259–273

Porada H (1989) Pan-african rifting and Orogenesis in Southern to Equatorial Africa and Eastern Brazil. Precambrian Res 44:103–136 Porada H, Berhorst V (2000) Towards a new understanding of the Neoproterozoic-Early Paleozoic Lufilian and northern Zambezi belts in Zambia and the Democratic Republic of Congo. J Afr Earth Sci 30:727–771

Priestley K, Mckenzie D, Debayle E, Pilidou S (2008) The Africa upper mantle and its relationship to tectonics and surface geology.

Geophys J Int 175(3):1108–1126

Raucq P (1957) Contribution a` la connaissance du Syste`me de la Bushimay. Ann. Mus. Roy. Afr. Cent., Tervuren (Belgique), se´rie in-8, Sci Ge´ol, 18, 427 p

Raucq P (1970) Nouvelles acquisitions sur le syste`me de la Bushimay (Re´publique de´mocratique du Congo). Ann. Mus. Roy. Afr. Cent., Tervuren (Belgique), se´rie in-8, Sci Ge´ol, 69, 156 p

Ritsema J, van Heijst H (2000) New seismic model of the upper mantle beneath Africa. Geology 28(1):63–68

Sahagian DL (1993) Structural evolution of African basins: strati- graphic synthesis. Basin Res 5:41–54

Sandwell DT, Smith WHF (1997) Marine gravity anomaly from Geosat and ERS 1 satellite altimetry. J Geophys Res 102:10–039 Stankiewicz J, de Witt M (2013) 3.5 billion years of reshaped Moho,

southern Africa. Tectonophysics 609: 675–689

Tack L (1995) The Neoproterozoic Malagarazi supergroup of SE Burundi and its equivalent Bukoban Supergroup in NW Tanzania:

a current review. In: Wendorff M, Tack L (eds) Late Proterozoic belts in Central and Southwestern Africa. Annales du Muse´e royal de l’Afrique Centrale, Sciences Ge´ologiques, pp 121–129 Tack L, Wingate MTD, Lie´geois J-P, Fernandez-Alonzo M, Deblond A

(2001) Early Neoproterozoic magmatism (1000–910 Ma) of the

Zadinian and Mayumbian Groups (Bas-Congo), onset of Rodinia rifting at the western edge of the Congo Craton. Precambrian Res 110:277–306

Tack L, Delvaux D, Kadima E, Delpomdor F, Tahon A, Dumont P, Hanon M, Fernandez-Alonso M, Baudet D, Dewaele S, Cibambula E, Kanda Nkula V, Mpiana Ch (2008) The 1000 m thick Redbeds sequence of the Congo River Basin (CRB): a generally overlooked testimony in Central Africa of post-Gondwana amalgamation (550) and pre-Karoo break-up (320 Ma). 22nd Colloquium African Geo- logy (CAG22), Hammamet, Tunisia, Abstracts volume, 4–6 November 2008, pp 86–88

Tack L, Wingate MTD, De Waele B, Meert J, Belousova E, Griffin A, Tahon A, Fernadez-Alonso M (2010) The 1375 Ma "Kibaran event"

in Central Africa: prominent emplacement of bimodal magmatism under extensional regime. Precambrian Res 180:63–84

Tait J, Delpomdor F, Pre´at A, Tack L, Straathof G, Kanda Nkula V (2011) Neoproterozoic sequences of the West Congo and Lindi/

Ubangi Supergroups in the Congo Craton, Central Africa. In:

Arnaud E, Halverson GP, Shields-Zhou G (eds) The geological record of Neoproterozoic Glaciation, vol 36. Geol Soc, London, Mem, pp 185–194

Tapley B, Ries J, Bettadpur S, Chambers D, Cheng M, Condi F, Gunter B, Kang Z, Nagel P, Pastor R, Pekker T, Poole S, Wang F (2005) GGM02-An improved Earth gravity field model from GRACE.

J Geod 79:467–478

Verbeek T (1970) Ge´ologie et lithologie du Lindien (Pre´cambrien Supe´rieur du nord de la Re´publique De´mocratique du Congo).

Ann. Mus. Roy. Afr. Cent., Tervuren (Belgique), se´rie in-8, Sci Ge´ol, 66, 311 pp

Vicat J-P, Pouclet A (1995) Nature du magmatisme lie´ a` une extension pre´-panafricaine: les dole´rites des bassins de Comba et de Sembe´- Ouesso (Congo). Bulletin de la Socie´te´ Ge´ologique de France 166(4):355–364

Vicat J-P, Vellutini P-J (1987) Sur la nature et la signification des dole´rites du bassin pre´cambrien de Se`mbe-Ouesso (Re´publique du Congo). Precambrian Res 37:57–69

Vicat J-P, Gioan P, Albouy Y, Cornacchia M, Giorgi L, Blondin P (1989) Mise en e´vidence, sur la bordure ouest du craton du Congo, de fosses d ’ effondrement d ’ aˆge Prote´rozoique supe´rieur, masque´s par les formations phane´rozoı¨ques de la cuvette du Zaı¨re.

Comptes Rendus de l ’ Acade´mie des Sciences, se´rie II A 309:


Villeneuve M (1983) Les sillons tectoniques du Precambrien superieur dans l’Est du Zaire. Comparaisons avec les directions du rift est- africain. Bull Centres Rech Explor-Prod Elf-Aquitaine 7(1):


Waleffe A (1988) Etude photoge´ologique du synclinorium de l’Itombwe et des re´gions avoisinantes au Sud du 3e` paralle`le Sud (Kivu, Zaire). Bulletin de la Socie´te´ belge de Ge´ologie 97(2):



Documents relatifs

(1) University Heidelberg, Institute of Earth Sciences, Institute of Earth Sciences, Thermochronology and Archaeometry, Heidelberg, Germany

The Congo Basin (also called Cuvette Centrale) in the Democratic Republic of the Congo (DRC) is probably the last continental-scale sedimentary basin that is

The southern KC comprises an unmetamorphosed Mesoarchean granitic complex of limited extent (ca. 3.0 Ga SHRIMP zircon ages) surrounded over large areas by migmatitic

L’archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des

implications for the Neoproterozoic tectonic evolution of the eastern Jiangnan orogen. Detrital zircon geochronology of

Fortunately, however, since the subgenus Anguilloclarias is absent from the Lower Congo and the Pool Malebo, the serration of the inner side of the pectoral spine remains a

Low-angle slickensided fault planes are observed in the Samba cored well, constraining the onset of the recent compressional setting in the late Albian, at a time when South America

This report on forests and climate change produced by the Central African Forest Commission COMIFAC with the support of its partners aims to update the international community and

The Lajin cross-section (transect C) ... Cross-sections A, B and D in the Western High Zagros ... Geometry and Kinematics of the Eastern High Zagros ... The Faraghan cross-section

86. Dans les années 2000, la CSST, à l’image de ses homologues des autres provinces canadiennes, devient en fait le principal garant de la viabilité d’une offre privée de

Les interfaces, graphiques ou physiques, guident et influencent notre perception du contenu des données. Elles définissent notre expérience et par le fait même la

Western Europe the Chamrousse ophiolite com¬ plex, Western Alps France Contr Mineral Petrol, 96,406^113 Rutishauser, H 1973 Die quantitative Erfassung von Migmatiten

Par lettres en date du 8 juillet 2020, le greffier a informé les Parties que, tout en poursuivant l’examen de l’ensemble des chefs de préjudice invoqués par le demandeur et des

Nous avons évalué l’impact d’une glycé- mie anormale (depuis l’hyperglycémie à jeun (IFG) jusqu’au DT2) sur la com- position corporelle (DXA) chez des individus de plus de 45

La centralisation est une technique d'organisation administrative dans laquelle toute l'action exécutoire est exercée au nom et pour le compte d'une personne morale de droit public

Plus précisément, nous détaillons cinq indicateurs d’ordre mésoscopique (les thèmes disciplinaires abordés dans les.. séances, leurs contextes de traitement, les phases de

-..-..■ .- During the period 1963 - 1965* in spite of unfavourable circumstances, the overall activities of the Institut Geographique du Congo have pro..

In the general population the risk is related to the availability of safe food and water. The disease causes epidemics particularly in complex emergency settings where the above

World Health Organization Communicable Diseases Working Group on Emergencies 11 FIGURE 2: VIRAL HAEMORRHAGIC FEVER OUTBREAK CONTROL.. Identify suspected cases of viral

Ministère du Plan et Suivi de la Mise en œuvre de la Révolution de la Modernité - MPSMRM/Congo, Ministère de la Santé Publique - MSP/Congo and ICF International..

Emery Kalema (Postdoc Fellow at Chair in Historical Trauma and Transformation, Stellenbosch University, Republic of South Africa - Center for the Study of Africa and

universitaires, artistes, écrivains, acteurs culturels, journalistes et blogueurs, activistes et autres) ; le devenir de la culture congolaise (nouveaux lieux de création et

Prise en charge des douleurs aiguës sévères par le médecin généraliste : rapport du système ”Médecin Correspondant SAMU” au sein du réseau des médecins de montagne..